2,374 research outputs found
SisÀilman laatuun vaikuttavat tekijÀt
TiivistelmĂ€. TĂ€mĂ€n kandidaatintyön tavoitteena on esitellĂ€ sisĂ€ilman laatuun vaikuttavia tekijöitĂ€. NĂ€ihin tavoitteisiin pÀÀstiin tutustumalla aihealueen keskeisiin tutkimuksiin. Työn tavoitteena oli luoda selkeĂ€ ja helposti ymmĂ€rrettĂ€vĂ€ kokonaisuus erilaisista sisĂ€ilmatekijöistĂ€. Työ on rajattu sisĂ€ilman laatuun vaikuttaviin tekijöihin ja ne on pyritty avaamaan mahdollisimman tarkasti. SisĂ€ilman laatuun vaikuttavat todella monet eri tekijĂ€t yhdessĂ€ ja erikseen. SisĂ€ilmaongelmia epĂ€iltĂ€essĂ€ onkin haastavaa yksilöidĂ€ sen lĂ€hteitĂ€. SelkeitĂ€ ohjeita ja raja-arvoja ei ole vielĂ€kÀÀn saatavilla ongelmien osoittamiseksi. HyvĂ€n sisĂ€ilman takaamiseksi on tĂ€rkeÀÀ huolehtia talotekniikan ja rakenteiden kunnosta sekĂ€ siisteydestĂ€. Ennakointi onkin avainasemassa sisĂ€ilmaongelmien ja niistĂ€ aiheutuvien terveyshaittojen ehkĂ€isemisessĂ€.Factors that influence indoor air quality. Abstract. The aim of this bachelorâs thesis is to get acquainted with the factors influencing indoor air quality. These objectives were achieved by reviewing key studies in the field. The aim of the thesis was to create a clear and easily understandable set of different indoor air factors. The work is limited to the factors affecting indoor air quality, and efforts have been made to open these as closely as possible. There are many different factors that influence the quality of indoor air together and separately. It is therefore challenging to identify the sources of indoor air quality problems. Clear guidelines and thresholds are still not available to address the problems. In order to ensure good indoor air, it is important to maintain the integrity and cleanliness of the building technology and structures. Foresight is therefore a key element in preventing indoor air problems and the resulting health damage
Picosecond timing of Microwave Cherenkov Impulses from High-Energy Particle Showers Using Dielectric-loaded Waveguides
We report on the first measurements of coherent microwave impulses from
high-energy particle-induced electromagnetic showers generated via the Askaryan
effect in a dielectric-loaded waveguide. Bunches of 12.16 GeV electrons with
total bunch energy of GeV were pre-showered in tungsten, and
then measured with WR-51 rectangular (12.6 mm by 6.3 mm) waveguide elements
loaded with solid alumina () bars. In the 5-8 GHz
single-mode band determined by the presence of the dielectric in the waveguide,
we observed band-limited microwave impulses with amplitude proportional to
bunch energy. Signals in different waveguide elements measuring the same shower
were used to estimate relative time differences with 2.3 picosecond precision.
These measurements establish a basis for using arrays of alumina-loaded
waveguide elements, with exceptional radiation hardness, as very high precision
timing planes for high-energy physics detectors.Comment: 16 pages, 15 figure
Puhalluseristettyjen ylÀpohjien lÀmpötekniset ominaisuudet ja niiden mitoitus
TiivistelmÀ. Työn tarkoituksena on tutustua puhalluseristettyjen ylÀpohjien lÀmpöteknisiin ominaisuuksiin. Rakennushankkeeseen pakolliseksi tuleva elinkaarimallin mukainen hiilijalan- ja hiilikÀdenjÀljen laskenta suoritetaan 140 neliömetrin omakotitalon ja 3000 neliömetrin maatalousrakennuksen lÀmmöneristeille. Niiden avulla lÀmmöneristeen valinnasta johtuvia ympÀristövaikutuksia pystytÀÀn vertailla. TyössÀ lasketaan erilaisilla hyvÀksyttÀvillÀ menetelmillÀ lÀmmönlÀpÀisykerroin tyypilliselle ylÀpohjarakenteelle ja tuloksia verrataan aikaisempien tutkimusten pohjalta laskettuihin todellisia olosuhteita vastaaviin arvoihin. U-arvot lasketaan EN-standardien, RIL:n suunnitteluohjeen ja COMBI-hankkeen tuloksista johdettujen arvojen mukaisesti. COMBI-hankkeen tulokset kuvaavat todellisia ylÀpohjan olosuhteita.
Selluvillan ympÀristövaikutukset ovat huomattavasti pienemmÀt kuin mineraalivilloilla. TÀmÀ nÀkyy pienenÀ hiilijalanjÀlkenÀ. Selluvilla on myös ainut puhallettava lÀmmöneriste, joka sitoo hiiltÀ ja jolla on hiilikÀdenjÀlki. Tulokset osoittavat, ettÀ EN-standardien mukainen mitoitus antaa huomattavasti todellista tilannetta paremmat U-arvot kaikille puhallettaville lÀmmöneristeille. SisÀinen konvektio alkaa monien tutkimusten mukaan jo pienillÀ lÀmpötilaeroilla ja kerrospaksuuksilla. RIL:n suunnitteluohjeen mukainen mitoitus on pienemmÀn ilmanlÀpÀisevyyden omaavalla selluvillalla lÀhes todellisia tilanteita vastaava. Suuremman ilmanlÀpÀisevyyden omaavan lasivillan tapauksessa ohje antaa liian pieniÀ lÀmmönlÀpÀisykertoimia. Lasivillalla myös eristekerroksen pintaan vaikuttava ilmavirtaus lisÀÀ huomattavasti lÀmpövirtaa eristeen lÀpi.
U-arvon laskenta on jatkossa suositeltavaa tehdĂ€ RIL:n suunnitteluohjeen mukaisesti. Ohjeessa otetaan ilmanlĂ€pĂ€isevyys huomioon lisĂ€terminĂ€. Tulosten mukaan lisĂ€termin kerroin on suurilla ilmanlĂ€pĂ€isevyyksillĂ€ riittĂ€mĂ€tön. HyvĂ€ksyttĂ€vĂ€ssĂ€ lĂ€mmönlĂ€pĂ€isykertoimen laskennassa tulisi aina ottaa ilmanlĂ€pĂ€isevyys huomioon erityisesti Suomen kaltaisissa kylmissĂ€ ilmasto-oloissa.Thermal properties and design of loose-fill insulated roofs. Abstract. The purpose of the work is to find out the thermal properties of the loose-fill insulated roofs. The calculation of the carbon footprint and carbon handprint, which will be mandatory for the construction project, will be carried out in 140 mÂČ for the heat insulation of the detached house and 3000 mÂČ for the agricultural building. They make it possible to compare the environmental impacts of heat insulation selection. The work is calculated using different acceptable methods to calculate the heat permeability factor for the typical superstructure and the results are compared to the actual values calculated from previous studies. U-values shall be calculated in accordance with ENstandards, RIL design guidelines and values derived from the results of the COMBIproject. The results of the COMBI-project reflect the real conditions of the loose-fill insulated roofs.
The environmental impact of wood fibre insulation is significantly lower than mineral wools. This can be seen as a small carbon footprint. Wood fibre insulation is also the only loose-fill insulation that binds carbon and has a carbon handprint. The results show that design according to EN-standard gives significantly better U-values than the actual situation for all loose-fill insulations. According to many studies, internal convection begins with small temperature differences and layer thicknesses. The design according to the RIL design guidelines is almost equivalent to the actual situation for loose-fill insulations with a lower air transmittance. Materials with a greater air transmittance like glass wool, the instructions provide too small heat transmittance factors. In glass wool, the air flow affecting the surface of the insulation layer also significantly increases the heat flow through the insulation.
In the future, it is recommended to calculate the U-value according to RILâs design instructions. In the instructions, air permeability is taken into account as an additional term. According to the results, the coefficient of the additional term is insufficient for greater air permeability. Air permeability should always be taken into account in an acceptable heat transfer coefficient calculation, especially in cold climates like Finland
Prefrontal microcircuit underlies contextual learning after hippocampal loss
Specific brain circuits have been classically linked to dedicated functions. However, compensation following brain damage suggests that these circuits are capable of dynamic adaptation. Such compensation is exemplified by Pavlovian fear conditioning following damage to the dorsal hippocampus (DH). Although the DH normally underlies contextual fear and fear renewal after extinction, both can be learned in the absence of the DH, although the mechanisms and nature of this compensation are currently unknown. Here, we report that recruitment of alternate structures, specifically the infralimbic and prelimbic prefrontal cortices, is required for compensation following damage to the hippocampus. Disconnection of these cortices in DH-compromised animals and immediate early gene induction profiles for amygdala-projecting prefrontal cells revealed that communication and dynamic rebalancing within this prefrontal microcircuit is critical. Additionally, the infralimbic cortex normally plays a role in limiting generalization of contextual fear. These discoveries reveal that plasticity through recruitment of alternate circuits allows the brain to compensate following damage, offering promise for targeted treatment of memory disorders
The Electromagnetic Background Environment for the Interaction-point Beam Feedback System at the ILC
Accelerator measurements of magnetically-induced radio emission from particle cascades with applications to cosmic-ray air showers
For fifty years, cosmic-ray air showers have been detected by their radio
emission. We present the first laboratory measurements that validate
electrodynamics simulations used in air shower modeling. An experiment at SLAC
provides a beam test of radio-frequency (RF) radiation from charged particle
cascades in the presence of a magnetic field, a model system of a cosmic-ray
air shower. This experiment provides a suite of controlled laboratory
measurements to compare to particle-level simulations of RF emission, which are
relied upon in ultra-high-energy cosmic-ray air shower detection. We compare
simulations to data for intensity, linearity with magnetic field, angular
distribution, polarization, and spectral content. In particular, we confirm
modern predictions that the magnetically induced emission in a dielectric forms
a cone that peaks at the Cherenkov angle and show that the simulations
reproduce the data within systematic uncertainties.Comment: 5 pages, 7 figure
Observations of the Askaryan Effect in Ice
We report on the first observations of the Askaryan effect in ice: coherent impulsive radio Cherenkov radiation from the charge asymmetry in an electromagnetic (EM) shower. Such radiation has been observed in silica sand and rock salt, but this is the first direct observation from an EM shower in ice. These measurements are important since the majority of experiments to date that rely on the effect for ultra-high energy neutrino detection are being performed using ice as the target medium. As part of the complete validation process for the Antarctic Impulsive Transient Antenna (ANITA) experiment, we performed an experiment at the Stanford Linear Accelerator Center (SLAC) in June 2006 using a 7.5 metric ton ice target, yielding results fully consistent with theoretical expectations
Observations of Microwave Continuum Emission from Air Shower Plasmas
We investigate a possible new technique for microwave measurements of
ultra-high energy cosmic ray (UHECR) extensive air showers which relies on
detection of expected continuum radiation in the microwave range, caused by
free-electron collisions with neutrals in the tenuous plasma left after the
passage of the shower. We performed an initial experiment at the AWA (Argonne
Wakefield Accelerator) laboratory in 2003 and measured broadband microwave
emission from air ionized via high energy electrons and photons. A follow-up
experiment at SLAC (Stanford Linear Accelerator Center) in summer of 2004
confirmed the major features of the previous AWA observations with better
precision and made additional measurements relevant to the calorimetric
capabilities of the method. Prompted by these results we built a prototype
detector using satellite television technology, and have made measurements
indicating possible detection of cosmic ray extensive air showers. The method,
if confirmed by experiments now in progress, could provide a high-duty cycle
complement to current nitrogen fluorescence observations of UHECR, which are
limited to dark, clear nights. By contrast, decimeter microwave observations
can be made both night and day, in clear or cloudy weather, or even in the
presence of moderate precipitation.Comment: 15 pages, 13 figure
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